Fertilizer blade assemblies are employed by farmers to deliver nitrogen enriching fertilizers such as anhydrous ammonia to a targeted zone beneath the surface of the soil of a crop field while causing a minimum of disruption to the structure of the upper layer of the topsoil while causing significant disruption of the soil within two or three inches of the lower soil working portion of the blade assembly. Fertilizer blade assemblies are used by farmers who are practicing “strip-till” cultivation. Strip-till cultivation is a method of farming in which the disturbance of the soil at the surface is minimized. Strip-till cultivation usually creates a strip of dark soil at the surface typically between 2 and 10 inches in width where a fertilizer knife passes through the surface. Thus the term “strip-till”. This darker strip of soil will also warm faster in the spring which is beneficial for germination and growth. By preserving most of the structure of the upper layer of topsoil, farmers can protect the moisture retaining capacity of the soil and also make it easier for new crop plants to put down roots. Typically, fertilizer implements carry patterns of fertilizer blade assemblies spaced for simultaneously delivering fertilizer to a plurality of parallel furrows. The placement and control of such fertilizer blades is conducted with extreme precision—typically on the order of +/− one inch. This is made possible with Global Positioning System (GPS) technology in combination with local transmitter devices that allow the farmer to control implement location with such precision. Thus, for example, the farmer is able to apply precisely targeted fertilizer and then return at a later time to plant seeds in strips of soil that exactly corresponds to the strips of soil that received fertilizer.
Typical prior art fertilizer applicator blades are one-piece structures having a shank member with a blade portion. The shank member is typically an elongated steel plate which, when in use, slants down and forward into the soil and is usually bolted to one of a plurality of the machine shanks of a fertilizer implement. A typical prior art blade portion is either integral with the shank plate or permanently welded to the shank plate and provides a hard sharp leading edge. A fertilizer tube is also welded to the trailing edge of the shank plate. With a typical prior art fertilizer blade, the fertilizer tube is welded to the back of the blade's shank member and the fertilizer tube terminates at the base of the shank member and delivers liquid fertilizer to the furrowed soil at that location as the blade assembly cuts through the soil. With prior art fertilizer applicator blades, when part of the fertilizer applicator blade is too worn for use, the entire blade is removed and replaced.
Single piece fertilizer applicator blades have another important disadvantage. In many cases farmers will need to perform a strip-till operation in a first field, such as a cornfield, and then will need to perform a low-draft till operation in a second field, such as a soybean field. In order to transfer a fertilizing rig from the first field to the second field, a farmer must remove all of the strip-till blade assemblies from the machine and replace them with low-draft blade assemblies. Typically, these machines carry as many as 16 fertilizer knife assemblies, and, for each fertilizer knife, the farmer must unclamp and disconnect the fertilizer tube, remove the bolts securing the knife shank to the machine shank and do much of this work in an area that is obstructed by other components of the machine. Typically, such a change might require as much as three hours for a 16 blade rig. The delay involved in changing blade assemblies represents a significant cost. But, such a delay is particularly troublesome if the farmer is attempting to complete an operation in a field prior to the onset of bad weather.
Present fertilizer blade assemblies have yet another disadvantage. The fertilizer tube mounted on the back surface of the knife shank is typically exposed to the passage of soil that eventually wears and destroys the fertilizer tube.
Accordingly, what is needed is a fertilizer blade assembly having a blade shank that is adapted to receive points that can be removed and replaced and further to receive a strip-till point adapted for strip-till operations between 6 and 12 inches below the surface and a low-draft point adapted for operations in a zone between 4 and 7 inches below the surface. Further, it would be advantageous if the shanks and points included additional side flanges that extend on both sides of the fertilizer tube running down the back edge of the knife shank thereby enclosing and protecting the fertilizer tube from wear thereby prolonging the life of the fertilizer tube.